JP6140464B2 - Data transmission method and apparatus in wireless communication system - Google Patents

Description

  The present invention relates to a data transmission method and apparatus in a wireless communication system.

  Recently, active research on broadband wireless communication systems is ongoing. In a broadband wireless communication system, before data is transmitted, the modulation scheme and error correction coding rate of the transmitted data are determined so as to be suitable for the channel environment. For example, in a broadband wireless communication system, a modulation and coding scheme (MCS) level for downlink transmission is determined by the following method.

  When a base station receives a response signal to channel state information and downlink data, that is, an ACK (Acknowledgement) / NACK (Negative Acknowledgement) signal from the terminal, the base station determines whether Determine the channel state. Further, the base station detects the MCS level corresponding to the channel state determined based on the MCS determination table including the predetermined MCS level information for each channel state. Thereafter, the base station transmits downlink data to the terminal using the detected MCS level.

  As described above, conventionally, the MCS level is determined based on only the channel state information and the ACK / NACK signal received from the terminal without considering the interference in the actual terminal channel environment. Therefore, it is difficult to determine the MCS level by accurately reflecting the channel state of the terminal.

Korean Patent Publication No. 2004-0037194 Korean Patent Publication No. 2008-0063109

  Accordingly, the present invention has been proposed in order to solve the above-described problems of the prior art, and an object thereof is to provide a data transmission method and apparatus in a wireless communication system.

  It is another object of the present invention to provide a method and apparatus for determining an MCS level suitable for a channel condition of a receiver based on whether or not interference control is possible in a wireless communication system.

  Another object of the present invention is to provide a method and apparatus for enabling data transmission efficiency to be improved using an MCS level corresponding to a channel state of a receiver considering interference in a wireless communication system. It is in.

  To achieve the above object, according to an aspect of the present invention, a data transmission method of a base station in a wireless communication system is provided. The method includes a step of transmitting a response signal and channel state information for downlink data received from a terminal to a central coordinator, receiving scheduling information from the central coordinator, and for receiving an adjacent base station based on the scheduling information Determining an interference control mode determined according to whether or not interference control is performed, and transmitting data to the terminal using a modulation and coding scheme (MCS) level according to the determined interference control mode. It is characterized by having.

  According to another aspect of the present invention, a scheduling information transmission method for a central coordinator in a wireless communication system is provided. The method receives a response signal and channel state information for downlink data from each of a plurality of base stations, and determines a scheduling metric for determining a scheduling priority based on the response signal and the channel state information. A step of performing scheduling for terminals connected to each of the plurality of base stations based on the determined scheduling metric, and transmitting the scheduling result to the plurality of base stations. Features.

  According to yet another aspect of an embodiment of the present invention, a base station in a wireless communication system is provided. The base station receives a response signal and channel state information for downlink data from a terminal, a central unit that transmits the response signal and channel state information to a central adjustment unit, and receives scheduling information from the central adjustment unit An interface unit, a control unit that determines an interference control mode determined based on whether or not interference control is performed on an adjacent base station based on the scheduling information, and modulation and coding according to the determined interference control mode And a transmission unit that transmits data to the terminal using a scheme (MCS) level.

  According to yet another aspect of an embodiment of the present invention, a central coordinator in a wireless communication system is provided. The central coordinator receives a response signal and channel state information for downlink data from each of a plurality of base stations, and scheduling for determining a scheduling priority based on the response signal and channel state information A base station interface configured to determine a metric, perform scheduling for a terminal connected to each of the plurality of base stations based on the determined scheduling metric, and transmit the scheduling result to the plurality of base stations And a scheduler for outputting the data.

  The present invention has the advantage that the channel state of the receiver according to the interference control state can be more clearly determined in the wireless communication system. Further, the data transmission efficiency can be improved by determining the MSC level according to the channel state of the receiver that is clearly determined.

It is a signal flow figure which shows the data transmission method in the conventional radio | wireless communications system. It is a block diagram which shows the structure of the MCS level determination part contained in the base station in the conventional radio | wireless communications system. 1 is a diagram illustrating a wireless communication system according to an embodiment of the present invention. It is a block diagram which shows the structure of the base station by embodiment of this invention. It is a block diagram which shows the structure of the MCS level determination part contained in the base station by embodiment of this invention. It is a block diagram which shows the structure of the center adjustment part by embodiment of this invention. It is a block diagram which shows the structure of the scheduler contained in the center adjustment part by embodiment of this invention. 5 is a signal flowchart between a central adjustment unit and a base station according to an embodiment of the present invention. 6 is a flowchart illustrating steps of transmitting scheduling information by a central coordinator according to an embodiment of the present invention. 5 is a flowchart illustrating a process of determining an MCS level in a base station according to an embodiment of the present invention.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. Further, in the following description, in order to clarify only the gist of the present invention, specific descriptions of related known functions and configurations are appropriately omitted.

  The present invention provides a data transmission method and apparatus in a wireless communication system. Specifically, a transmitter in a wireless communication system transmits data to the receiver, receives a response signal indicating whether or not the received data has been successfully received, and channel state information from the receiver, and transmits the data. The interference control mode set at the time point is determined, the channel state information is changed based on the determined interference control mode and the response signal, and the modulation and coding scheme corresponding to the changed channel state information (Modulation and Coding Scheme) : MCS) level and method and apparatus for transmitting data to a receiver.

  In the following, an example will be described in which the transmitter is a base station and the receiver is a terminal. However, it will be apparent to those skilled in the art that each of the transmitter and the receiver is not limited to a base station and a terminal, and can be variously modified.

  Prior to the description of the embodiments of the present invention, a data transmission method and apparatus in a conventional wireless communication system will be described.

  FIG. 1 is a signal flow diagram illustrating a data transmission method in a conventional wireless communication system.

  Referring to FIG. 1, the base station 100 requests channel state information from the terminal 120 in step 101. In step 102, the terminal 120 estimates a channel using the pilot signal or preamble signal transmitted from the base station 100, and transmits channel state information including the state information regarding the channel estimated in step 103 to the base station 100. To do.

  The channel state information may include a channel coefficient or a signal to interference plus noise ratio (SINR), but in general, the channel state information includes SINR based on system complexity. Therefore, in the following, it should be noted that channel state information may be mixed with SINR.

  In step 104, the base station 100 transmits downlink data to the terminal 120. In step 105, the base station 100 receives a response signal to the transmitted downlink data, that is, an ACK (Acknowledgement) / NACK (Negative Acknowledgement) signal.

  Also, the base station 100 determines an MCS level based on the received SINR and ACK / NACK signal in step 106, and transmits downlink data to the terminal 120 using the determined MCS level in step 107. .

  Here, step 106 will be specifically described as follows. Base station 100 determines the MCS level based on a predetermined MCS determination table using SINR. However, the MCS determination table cannot perfectly reflect all channel environments actually operated by the wireless communication system.

  Therefore, base station 100 uses an adaptive channel state information adjustment method (hereinafter referred to as “Outer-Loop Rate Control (hereinafter referred to as“ OLRC ”) method”). The OLRC scheme is a scheme in which the base station 100 changes the SINR value received from the terminal 120 using the ACK / NACK signal received from the terminal 120.

  Specifically, when the base station 100 receives an ACK signal from the terminal 120 after transmitting downlink data, the base station 100 changes the SINR value using Equation 1 below. When the base station 100 receives a NACK signal from the terminal 120 after transmitting downlink data, the base station 100 changes the SINR value using Equation 2 below.

In Equations 1 and 2, SINR_in indicates the SINR value received from the terminal 120, SINR_out indicates the changed SINR value, Target PER (Packet Error Rate) indicates the target packet error probability, and Offset _{k− 1} indicates an offset value used to change SINR_in at time k−1, Offset _k indicates an offset value used to change SINR_in at time k, and DOWN is a predetermined value. UP indicates a value determined based on DOWN and Target PER.

  As shown in Equations 1 and 2, the base station 100 increases SINR_in by UP when receiving an ACK signal from the terminal 120, and sets SINR_in when receiving an NACK signal from the terminal 120. Decrease by DOWN.

  As described above, when the SINR value is changed, the base station 100 determines an MCS level corresponding to the changed SINR value, and uses the determined MCS level to transmit downlink data to the terminal 120. Send.

  Hereinafter, the MCS level determination unit used to determine the MCS level of the base station 100 will be described in detail with reference to FIG.

  FIG. 2 is a block diagram illustrating a configuration of an MCS level determination unit included in a base station in a conventional wireless communication system.

  Referring to FIG. 2, the MCS level determination unit 200 includes an OLRC unit 210 and an MCS level detection unit 220.

  When the SIRC value is received from the terminal, the OLRC unit 210 receives one of Equations 1 and 2 according to whether an ACK signal or a NACK signal is received for the transmitted downlink data. To change the received SINR value. In addition, the OLRC unit 210 outputs the changed SINR value to the MCS level detection unit 200.

  The MCS level detection unit 200 detects and outputs the MCS level corresponding to the changed SINR value from a predetermined MCS level determination table, so that the detected MCS level transmits downlink data to the terminal. To be able to be used.

  As described above, in the conventional wireless communication system, the base station only changes the SINR received from the terminal based on whether the ACK signal or the NACK signal is received for determining the MCS level. Interference was not considered at all.

  Accordingly, an embodiment of the present invention proposes a method and apparatus for enabling an MCS level to be determined adaptively to a terminal channel condition by more accurately determining a channel condition of the terminal considering interference. .

  FIG. 3 is a diagram illustrating a wireless communication system according to an embodiment of the present invention.

  Referring to FIG. 3, the wireless communication system includes a terminal 300, a plurality of cells (ie, a first cell 310, a second cell 320, and a plurality of base stations managing each of the third cells 330 (ie, The first base station 311, the second base station 321, the third base station 331, and a central coordinator 340 that controls a plurality of base stations are included in FIG. An example will be described in which a plurality of cells are included, and a plurality of base stations include three base stations. However, the number of the plurality of cells and the base stations is not limited to this and may be variously changed. Of course you can.

  In the wireless communication system shown in FIG. 3, interference between cells occurs when cells are adjacent to each other. For example, in the case of downlink transmission / reception, when the first base station 311 transmits a signal to the terminal 300 included in the first cell 310, the second base station 321 and the third base station Signals transmitted from the second base station 321 and the third base station when performing a transmission operation can act on the terminal 300 as an interference signal. When such inter-cell interference occurs, there is a problem that not only the communication quality is deteriorated but also the processing amount for signal transmission / reception is reduced.

  Therefore, in order to prevent such a problem, various interference control schemes can be used in the embodiment of the present invention. For example, by executing scheduling according to signal and data transmission / reception via communication between the first base station 311, the second base station 321, and the third base station 331, two during a specific time period An interference control scheme that prevents the above base stations from simultaneously performing communication can be used. Further, according to the scheduling of the central adjustment unit 340, the base station that transmits signals and data during the corresponding time period is excluded from the first base station 311, the second base station 321, and the third base station 331. An interference control scheme for controlling the transmission power of the remaining base stations can be used. In this case, the central adjustment unit 340 can select an optimum terminal for each cell based on the channel state of the terminal, and execute scheduling for assigning radio resources based on interference between cells. Each of the first base station 311, the second base station 321, and the third base station 331 receives the scheduling result from the central adjustment unit 340, and enters the cell-by-cell interference control mode determined according to the scheduling result. Based on this, the MCS level can be determined.

  The internal configuration of the base station according to the embodiment of the present invention will be described with reference to FIG.

  FIG. 4 is a block diagram showing a configuration of a base station according to the embodiment of the present invention.

  Referring to FIG. 4, the base station includes a receiving unit 400, a channel state information demodulating unit 402, an interference control mode buffer 403, an MCS level determining unit 404, an encoding and modulating unit 405, and a transmitting unit 406.

  Although not shown in FIG. 4, the receiving unit 400, the channel state information demodulating unit 402, the interference control mode buffer 403, the MCS level determining unit 404, the encoding and modulating unit 405, and the transmitting unit 406 are all controlled by the control unit. Perform the corresponding action below. In addition, the base station can include a separate physical configuration unit for performing communication with the central adjustment unit.

  The receiving unit 400 receives channel state information from the terminal. The channel state information may be periodically received from the terminal or received in response to a request from the base station. Also, the receiving unit 400 receives a response signal indicating whether or not the previously transmitted downlink data has been successfully received, that is, one of the ACK signal and the NACK signal from the terminal, thereby receiving the MCS. The data is output to the level determination unit 404.

  The channel state information demodulator 405 demodulates the received channel state information and acquires the SINR value included in the channel state information. Channel state information demodulation section 405 outputs the acquired SINR value to MCS level determination section 404.

The interference control mode buffer 403 stores an interference control mode at the time when downlink data is transmitted. Here, the interference control mode can be acquired based on the scheduling information received from the central adjustment unit, and indicates any one of the N interference control modes. Specifically, when there are k adjacent base stations that can affect the base station, N is 2 ^k , and the N interference control modes are determined according to the interference control states for the k base stations. It is determined. For example, when k is 2, the interference control modes are all four, and the following is performed according to whether interference control is performed on two base stations (that is, the first base station and the second base station). As shown in Table 1, the interference control mode can be classified. Further, all N interference control modes can be used as they are, but only a part of the N interference control modes (for example, two interference control modes) can be used.

  Referring to Table 1 above, the interference control mode (0) indicates a mode in which interference control for the first base station and the second base station is not executed, and the interference control mode (1) indicates interference for the first base station. The mode in which the control is executed is shown, the interference control mode (2) shows the mode in which the interference control for the second base station is executed, and the interference control mode (3) shows the first base station and the second base station The mode in which the interference control for is executed is shown.

  Here, in the interference control, the transmission power for the downlink data transmission of the first base station or the second base station is lowered to a predetermined value or less while the base station transmits the downlink data to the terminal. Or an operation for controlling the downlink data not to be transmitted in the first base station or the second base station during the time period in which the base station transmits the downlink data. The interference control can be executed according to the scheduling result of the central adjustment unit, and the scheduling operation of the central adjustment unit will be specifically described.

  When the ACK / NACK signal received at time t is input to the reception unit 400, the MCS level determination unit 404 receives interference from the interference control mode buffer 403 corresponding to the time when the downlink data transmission time is (t−k). Information on the control mode is read from the interference control mode buffer 403. Here, k indicates the time taken until the ACK / NACK signal is received after the corresponding downlink data is transmitted.

  The MCS level determination unit 404 changes the SINR value output from the channel state information demodulation unit 402 based on the ACK / NACK signal received at time t and information on the interference control mode corresponding to time (t−k). . The MCS level determination unit 404 determines the MCS level corresponding to the changed SINR value based on the MCS level determination table. Here, the MCS level determination table can be shown, for example, as shown in Table 2 below.

  As shown in Table 2 described above, the MCS level determination table is configured in a form in which the MCS level corresponds to each size range of the SINR value. The MCS level determination unit 404 outputs information on the determined MCS level to the encoding and modulation unit 405 when the MCS level is determined.

  The encoding and modulating unit 405 encodes and modulates downlink data to be transmitted to the terminal according to the determined MCS level. Transmitter 406 transmits downlink data to be encoded and modulated to the terminal.

  With reference to FIG. 5, the internal configuration of the MCS level determination unit 404 will be described in more detail.

  FIG. 5 is a block diagram illustrating a configuration of an MCS level determination unit included in a base station according to an embodiment of the present invention.

  Referring to FIG. 5, the MCS level determining unit includes N OLRC units 501-1 to 501-N, an SINR changing unit 502, and an MCS level detecting unit 503.

  The OLRC (0) unit 501-1 to OLRC (n) unit 501-N correspond to the interference control mode (0) to the interference control mode (n), respectively, and change the SINR value input according to the corresponding interference control mode. Determine the offset value used for That is, the OLRC (0) unit 501-1 to OLRC (N) unit 501-N receives the OLRC (0) unit 501-1 to 501-N when information on one of the n interference control modes is input. The OLRC unit corresponding to the input interference control mode among the OLRC (N) units 501-N uses the following Equation 3 and Equation 4 according to whether the ACK signal is received or the NACK signal is received, respectively. Determine the offset value.

  Equation 3 below shows an equation for changing an offset value used to change the SINR value in the interference control mode (n) when an ACK signal is received, and Equation 4 below shows: Fig. 4 shows a formula for changing an offset value used to change the SINR value in the interference control mode (n) when a NACK signal is received.

In Equations 3 and 4 above, Target PER (Packet Error Rate) indicates the target packet error probability, and Offset (n) _k-1 changes the SINR value at time point k-1 in the interference control mode (n). Offset (n) _k indicates the offset value used to change the SINR value at time k in the interference control mode (n), and DOWN indicates a predetermined value. UP indicates a value determined based on DOWN and Target PER.

  For example, when an ACK signal is received at time t and the interference control mode at time (tw) is the interference control mode (1), the OLRC (1) unit 501-2 corresponding to the interference control mode (1) Can determine an offset value for changing the SINR value input using Equation 3, and the SINR value input using Equation 4 when a NACK signal is received in the same situation. The offset value for changing can be determined.

  On the other hand, in the remaining OLRC units not corresponding to the interference control mode (1), the offset value can be determined using the following Equation 5 and Equation 6. That is, when an ACK signal is received in the interference control mode (1), the remaining OLRC unit determines an offset value using Equation 5 below, and a NACK signal is received in the interference control mode (1). In this case, the offset value is determined using Equation 6 below.

In Equation 5 and Equation 6 above, Offset (m) _k−1 is the offset value used to change the SINR value at time k−1 in the interference control mode (m) different from the interference control mode (n). Offset (m) _k indicates an offset value used to change the SINR value at time k in the interference control mode (m), and UP_non and DOWN_non indicate predetermined values.

  Of the OLRC (0) unit 501-1 to OLRC (N) unit 501-N, the output from the component corresponding to the corresponding interference control mode, that is, the offset value is output to the SINR changing unit 502. The SINR changing unit 502 changes the SINR value input using the input offset value using Equation 7 below.

  In Equation 7, SINR_in (n) represents the SINR value input to the MCS level determining unit, SINR_out represents the changed SINR value, and Offset (n) represents the corresponding interference control input to the SINR changing unit 502. Indicates the offset value corresponding to the mode.

  The SINR changing unit 502 outputs the changed SINR value to the MCS level detecting unit 503 when the SINR value is changed as described above. Thereafter, the MCS level detection unit 503 detects the MCS level corresponding to the changed SINR value from the MCS level determination table as shown in Table 1 above, and detects the detected MCS level for the MCS level for the terminal Determine as.

  With reference to FIG. 6, the internal configuration of the central adjustment unit according to the embodiment of the present invention will be described.

  FIG. 6 is a block diagram showing a configuration of the central adjustment unit according to the embodiment of the present invention.

  Referring to FIG. 6, the central adjustment unit includes a base station interface 600, a scheduler 602, and a memory 604.

  The base station interface 600 is a component for executing communication with each of a plurality of base stations, and receives channel state information and a response signal from each of the plurality of base stations. The channel state information is information indicating the channel state of the terminal, and is periodically received from each base station or received by an individual request, and can include an SINR value. In addition, the response signal may be any one of an ACK signal and a NACK signal indicating whether the reception of the downlink data is successful.

  The scheduler 602 determines a scheduling metric used for executing the base station-specific scheduling based on the channel state information and the response signal. The scheduling metric indicates a reference value for determining resource allocation priority, and may be, for example, a proportional fairness (PF) metric. The scheduler 602 can change the SINR value included in the channel state information based on whether the response signal is an ACK signal or a NACK signal, and can determine the changed SINR value as a scheduling metric.

  For example, when the response signal is an ACK signal, the scheduler 602 can increase the SINR value by UP, and when the response signal is a NACK signal, the scheduler 602 can decrease the SINR value by DOWN. Here, the offset values (UP, DOWN) used for changing the SINR value may be provided from each base station or may be a predetermined value.

  As described above, when the SINR value is changed, the scheduler 602 performs scheduling for each terminal of the plurality of base stations based on the changed SINR value. At this time, the scheduler 602 performs scheduling in consideration of interference between cells, and determines an interference control mode to be used for each time period according to the scheduling result. Therefore, the scheduler 602 transmits the scheduling result to each base station via the base station interface 600 so that the MCS level can be determined in consideration of the interference control mode.

  The memory 604 stores various information generated according to the operation of the central adjustment unit. For example, the memory 604 stores channel state information, response signals, and scheduling results received from each base station.

  With reference to FIG. 7, the internal configuration of scheduler 602 will be described in more detail.

  FIG. 7 is a block diagram illustrating a configuration of a scheduler included in the central adjustment unit according to the embodiment of the present invention.

  Referring to FIG. 7, the scheduler includes N OLRC units 701-1 to 701 -N, SINR change unit 702, M scheduling metric detection units 703-1 to 703 -M, and a scheduling calculation unit 704.

  The OLRC (0) unit 701-1 to OLRC (N) unit 701 -N correspond to each of the interference control mode (0) to the interference control mode (n), and the SINR value input according to the corresponding interference control mode. Determine the offset value used for the change. That is, the OLRC (0) unit 701-1 to OLRC (N) unit 701 -N receives the OLRC (0) unit 701-1 when information on one of n interference control modes is input. The OLRC unit corresponding to the input interference control mode in the OLRC (N) unit 701-N determines an offset value according to whether an ACK signal or a NACK signal is received.

  Similar to the base station, Equations 3 and 4 can be used to determine the offset value, where UP and DOWN used to change the SINR value are A value provided by the station or predetermined can be used. Alternatively, the offset value determination operation as described above is not performed, and an offset value used to change the SINR value may be directly provided from each base station.

  On the other hand, the remaining OLRC units that do not correspond to the input interference control mode can determine the offset value using Equation 5 and Equation 6 described above. Also in this case, in Formula 5 and Formula 6, UP_non and DOWN_non used to change the SINR value may be provided by each base station or may be a predetermined value. Alternatively, the offset value determination operation as described above is not performed, and an offset value used to change the SINR value may be directly provided from each base station.

  Of the OLRC (0) unit 701-1 to OLRC (N) unit 701 -N, the output from the component corresponding to the corresponding interference control mode, that is, the offset value is output to the SINR changing unit 702. Thereafter, the SINR changing unit 702 changes the SINR value input using the input offset value using Equation 7 described above.

  When the SINR value is changed as described above, the SINR change unit 702 outputs the changed SINR value to a corresponding one of the M scheduling metric detection units 703-1 to 703 -M.

  M scheduling metric detectors 703-1 to 703 -M detect the changed SINR values of terminals connected to the M base stations as scheduling metrics corresponding to the M base stations, respectively. To do. For example, the first scheduling metric detector 703-1 associated with the first base station among the M base stations detects the changed SINR value of the terminal connected to the first base station.

  The scheduling metrics detected from the M scheduling metric detection units 703-1 to 703 -M are output to the scheduling calculation unit 704. Thereafter, the scheduling operation unit 704 performs scheduling based on the scheduling metric, that is, the changed SINR value for each terminal of the M base stations. The scheduling calculation unit 704 outputs a scheduling result. At this time, the output scheduling result is transmitted to each of the M base stations. The scheduling result may include base station-specific interference control information. Accordingly, each of the M base stations can perform data transmission / reception based on the MCS level considering the interference control mode using time and radio resources according to the scheduling result.

  FIG. 8 is a signal flowchart between the central adjustment unit and the base station according to the embodiment of the present invention.

  Referring to FIG. 8, in step 801, the base station 800 transmits channel state information (SINR) and a response signal (ACK / NACK signal) received from the terminal to the central adjustment unit 820. Thereafter, in step 803, the central adjustment unit 820 determines a scheduling metric based on the received channel state information and the response signal. The scheduling metric indicates a reference value for determining the scheduling priority, and may be, for example, a SINR value changed based on a response signal.

  If the scheduling metric is determined, the central coordinator 820 performs scheduling using the determined scheduling metric in step 805. In addition, central adjustment section 820 transmits the scheduling result to base station 800 in step 807. The base station 800 transmits data to terminals in the cell using time and radio resources according to the scheduling result, and determines the MCS level based on information on the interference control mode included in the scheduling result at the time of data transmission. This determined MCS level can then be used. Next, the scheduling operation of the central adjustment unit 820 will be described with reference to FIG.

  FIG. 9 is a flowchart illustrating a process in which the central coordinator transmits scheduling information according to an embodiment of the present invention.

  Referring to FIG. 9, the central coordinator receives channel state information and a response signal from each of a plurality of base stations in step 900. In step 902, the central adjustment unit changes the received channel state information based on the response signal, and in step 904, the changed channel state information is determined as a scheduling metric. A scheduling metric can be determined for each of a plurality of base stations.

  Thereafter, the central coordinator performs scheduling for the terminals connected to each base station using the determined scheduling metric in step 906, and in step 908, information on resource allocation and information on interference control mode is obtained. The included scheduling result is transmitted to a plurality of base stations.

  A process of determining the MCS level at the base station will be described with reference to FIG.

  FIG. 10 is a flowchart illustrating a process of determining an MCS level in a base station according to an embodiment of the present invention.

  Referring to FIG. 10, the base station transmits downlink data to the terminal in step 1000. In step 1002, the base station receives one of an ACK signal and a NACK signal as a response signal indicating whether or not the reception of the channel state information and the transmitted downlink data is successful.

  In step 1004, the base station transmits the received channel state information and response signal to the central coordinator. In step 1006, the base station receives scheduling information from the central coordinator. Thereafter, in step 1008, the base station determines an interference control mode at the time of transmitting downlink data based on the received scheduling information. The interference control mode indicates a mode in which interference received from a plurality of adjacent base stations is controlled, and a plurality of interference control modes determined according to whether or not interference control is performed for each of the plurality of adjacent base stations. One of them is shown.

  Here, when any one of the ACK signal and the NACK signal is received at the first time point, the base station sets the second time point that precedes the first time period at the first time point. The determined interference control mode can be determined as the interference control mode at the time of transmitting downlink data. This first time period indicates the time taken to receive a response signal after transmitting downlink data.

  If the interference control mode is determined, the base station determines an offset value corresponding to the determined interference control mode in step 1010. The base station determines an offset value corresponding to the interference control mode determined based on whether the response signal is an ACK signal or a NACK signal. That is, the base station determines the offset value using Equation 3 described above when the response signal is an ACK signal, and determines the offset value using Equation 4 when the response signal is a NACK signal.

  On the other hand, the base station can additionally determine an offset value that does not correspond to the determined interference control mode. That is, based on whether the response signal is an ACK signal or a NACK signal, an offset value for changing the channel state information used in the determined interference control mode and other interference control modes is additionally determined. can do.

  In step 1012, the base station changes the received channel state information using the determined offset value. In step 1014, the base station determines the MCS level based on the changed channel state information.

  Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the scope and spirit of the invention. The scope of the present invention should not be limited to the above-described embodiments, but should be defined within the scope of the appended claims and their equivalents.

100, 311, 321, 331, 800 Base station 120, 300 Terminal 200, 404 MCS level determination unit 210, 501, 701 OLRC unit 220, 503 MCS level detection unit 310, 320, 330 Cell 340, 820 Central adjustment unit 400 Reception Unit 402 channel information sub-top unit 403 interference control mode buffer 405 encoding and modulating unit 406 transmitting unit 502, 702 SINR changing unit 600 base station interface 602 scheduler 604 memory 703 scheduling metric detecting unit 704 scheduling calculating unit

Claims (20)

A data transmission method for a base station in a wireless communication system, comprising:
Transmitting a response signal and channel state information for downlink data received from the terminal to a central coordinator that controls the base station and adjacent base stations ;
Receiving scheduling information including information on an interference control mode from the central coordinator, and determining the interference control mode at the time when the downlink data is transmitted based on the scheduling information;
Possess and transmitting data using the determined based on the interference control mode modulation and coding scheme (MCS) level to said terminal,
The interference control mode indicates whether downlink data transmission between the base station and the adjacent base station is controlled when the downlink data is transmitted to the terminal. . Transmitting the data comprises:
Changing the channel state information based on the determined interference control mode and the response signal;
Determining an MCS level corresponding to the changed channel state information;
The data transmission method according to claim 1, further comprising: transmitting the downlink data to the terminal using the determined MCS level. The step of changing the channel state information includes:
Determining an offset value corresponding to the determined interference control mode based on whether the response signal includes one of an ACK signal and a NACK signal;
The data transmission method according to claim 2, further comprising: changing the channel state information using the determined offset value. Determining the offset value comprises:
Generating a second adjustment value using a target packet error probability and a predetermined first adjustment value when the response signal includes the ACK signal;
Updating the offset value used corresponding to the determined interference control mode at a previous time point using the generated second adjustment value;
The data transmission method according to claim 3, further comprising: determining the updated offset value as the offset value corresponding to the determined interference control mode. The step of determining the interference control mode includes:
When the response signal is received at a first time point, it has a first second determining said interference control mode set at the time of earlier by time period in the first time point,
2. The data transmission method according to claim 1, wherein the first time period includes a time taken until the response signal is received after transmitting the downlink data. A scheduling information transmission method of a central coordinator in a wireless communication system,
Receiving a response signal and channel state information for downlink data from each of the base stations;
Determining a scheduling metric for determining a scheduling priority based on the response signal and channel state information;
Performing scheduling for terminals connected to each of the base stations based on the determined scheduling metric;
Possess and transmitting the result of the scheduling in the base station,
The scheduling result includes information on an interference control mode indicating whether or not downlink data transmission between the base station and an adjacent base station is controlled when downlink data is transmitted to the terminal. Scheduling information transmission method. Determining the scheduling metric comprises:
Changing the channel state information based on whether the response signal includes one of an ACK signal and a NACK signal;
The scheduling information transmission method according to claim 6, further comprising: determining the changed channel state information as the scheduling metric. The step of changing the channel state information includes:
Determining an offset value for changing the channel state information based on whether the response signal includes any one of the ACK signal and the NACK signal;
The scheduling information transmission method according to claim 7, further comprising: changing the channel state information using the determined offset value. Determining the offset value comprises:
Among the offset values received from each of the base stations, an offset value determined based on whether the response signal includes one of the ACK signal and the NACK signal is used as the channel state information. The scheduling information transmission method according to claim 8, further comprising a step of determining the offset value for changing the value. Determining the offset value comprises:
A first offset value stored for changing the channel state information when the response signal is the ACK signal and a memory for changing the channel state information when the response signal is the NACK signal. The scheduling information transmission method according to claim 8, further comprising a step of determining any one of the set second offset values as the offset value for changing the channel state information. A base station in a wireless communication system,
A receiving unit for receiving a response signal and channel state information for downlink data from the terminal;
A central interface unit that transmits the response signal and channel state information to a central adjustment unit that controls a base station and an adjacent base station, and receives scheduling information including information on an interference control mode from the central adjustment unit;
A control unit for determining an interference control mode at the time when the downlink data is transmitted based on the scheduling information;
The data using a modulation and coding scheme according to the determined interference control mode (MCS) level have a transmission unit that transmits to the terminal,
The base station is characterized in that the interference control mode indicates whether or not downlink data transmission between the base station and the adjacent base station is controlled when the downlink data is transmitted to the terminal . The controller is
The channel state information is changed based on the determined interference control mode and the response signal, and an MCS level corresponding to the changed channel state information is determined, and the down-down using the determined MCS level is performed. The base station according to claim 11, wherein the transmission unit is controlled to transmit link data to the terminal. The control unit determines an offset value corresponding to the determined interference control mode based on whether the response signal includes one of an ACK signal and a NACK signal, and determines the determined offset The base station according to claim 12, wherein the channel state information is changed using a value. When the response signal includes the ACK signal, the control unit generates a second adjustment value using a target packet error probability and a predetermined first adjustment value, and the generated second Using the adjusted value to update the offset value used corresponding to the determined interference control mode at a previous time, and using the updated offset value to correspond to the determined interference control mode The base station according to claim 13, wherein the base station is determined as a value. When the response signal is received at a first time point, the control unit determines the interference control mode set at a second time point preceding the first time period at the first time point,
The base station according to claim 11, wherein the first time period includes a time taken until the response signal is received after transmitting the downlink data. A central coordinator in a wireless communication system,
A base station interface for receiving a response signal and channel state information for downlink data from each of the base stations;
Determining a scheduling metric for determining a scheduling priority based on the response signal and the channel state information, performing scheduling for terminals connected to each of the base stations based on the determined scheduling metric, and the results of the scheduling have a scheduler to be output to the base station interface to transmit to the base station,
The scheduling result includes information on an interference control mode indicating whether or not downlink data transmission between the base station and an adjacent base station is controlled when downlink data is transmitted to the terminal. Central adjustment unit The scheduler changes the channel state information based on whether the response signal includes one of an ACK signal and a NACK signal, and determines the changed channel state information as the scheduling metric. The central adjustment unit according to claim 16, wherein The scheduler determines an offset value for changing the channel state information based on whether the response signal includes one of the ACK signal and the NACK signal, and determines the determined offset The central adjustment unit according to claim 17, wherein the channel state information is changed using a value. The scheduler determines an offset value determined based on whether the response signal includes one of the ACK signal and the NACK signal among the offset values received from each of the base stations. The central adjustment unit according to claim 18, wherein the offset is determined as the offset value for changing the channel state information. When the response signal is the ACK signal, the scheduler stores the first offset value stored for changing the channel state information and the channel state information when the response signal is the NACK signal. central adjustment unit according to claim 18, wherein determining the one of the second offset value stored in order to change as the offset value for changing the channel state information.

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